[TowerTalk] SteppIR

[Jim Lux]

On 2/27/15 1:52 PM, ve4xt at mymts.net wrote:
> The motors may be brushless, but because the element slides, the contacts from feedline to the element halves in the driven element is with tensioned tabs that press against the CuBe tape as it slides past.
> Those would be a potential failure point.
> 73, kellyve4xt
>
>>
  I wonder why you can't come up with an inductive or capacitive 
coupling to the ribbon?

Just back of the enveloping.. say you have a 30cm long, 2 cm wide 
"sandwich" with  plate on each side.. So the "plate area" is 120 square 
cm.  Figure the gap is 1mm (0.1cm), so the C is 8.8 pF/meter * 
0.012/.001 = 8.8*12 = 106 pF.


At 14 MHz the reactance is  1/(2*pi*14E6*106E-12)  about 100j ohms.. 
Kind of hard to cancel out. since at 28MHz it's 50j ohms